Robert had been worried that he wasn't pleasing Carla when he felt her press herself up against his tongue a second time, but she didn't do it again; when he realized that she was beginning to get even wetter than she'd been before, his fears were completely assuaged, leaving him free to enjoy what he was doing. The taste of his sister was a treat for Robert's taste buds, and knowing that he was arousing her just by using his mouth on her left him feeling rather pleased with himself. It wasn't long until he was totally focused on what he was doing between his sister's thighs.
Vic and Ellen had both watched the initial intimacy between their kids with horror and anguish, but as it had progressed, their reactions had gradually changed.
As he'd watched Robert's actions with his sister, Vic had gone from outrage at what his daughter was going through to consoling himself that at least Robert wasn't doing anything to hurt Carla. But the longer he stood there looking at his nude daughter, the more insistent the little voice in his head telling him how pretty she was became. Then the damn thing started pointing out how sexy she looked, and how she was responding to what her brother was doing to her-pointing out things that he'd willfully ignored: the faint flush she'd developed, how the ends of her breasts had erected and how hard her nipples had gotten, how willingly she'd sucked her brother's cock, and then how wet she was even before Robert started using his mouth on her. His reluctant awareness of her as a sexual being, grown and developed enough to engage in (and plainly enjoy!) the things their captors were having her do, combined with the sight of her lithe naked body to have him starting to feel a vague desire… the target of which he was unwilling to examine too closely.